Semiconductor memory device including a substrate, various interconnections, semiconductor member, charge storage member and a conductive member

ABSTRACT

According to one embodiment, a semiconductor memory device includes: a substrate; a first interconnect; a second interconnect; a plurality of third interconnects; a fourth interconnect; a semiconductor member; a charge storage member; and a conductive member. One of the plurality of third interconnects is disposed on two second-direction sides of the conductive member. Portions of the one of the plurality of third interconnects disposed on the two second-direction sides of the conductive member are formed as one body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/929,080, filed Jan. 2, 2019, which is a continuation of U.S.application Ser. No. 15/934,437, filed Mar. 23, 2018, which is acontinuation of U.S. application Ser. No. 15/455,443, filed Mar. 10,2017, which is based upon and claims the benefit of priority fromJapanese Patent Application No. 2016-047644, filed on Mar. 10, 2016; theentire contents of each of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a semiconductor memorydevice.

BACKGROUND

In recent years, a stacked semiconductor memory device has been proposedin which memory cells are integrated three-dimensionally. In such astacked semiconductor memory device, a stacked body in which electrodefilms and insulating films are stacked alternately on a semiconductorsubstrate is provided; and semiconductor pillars that pierce the stackedbody are provided. Then, memory cells are formed at each crossingportion of the electrode films and the semiconductor pillars. To realizeeven higher integration in such a stacked semiconductor memory device,it may be considered to dispose, between the semiconductor substrate andthe stacked body, a portion of a control circuit controlling the memorycells.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a semiconductor memory device according toa first embodiment;

FIG. 2 is a cross-section& view showing the semiconductor memory deviceaccording to the first embodiment;

FIGS. 3A and 3B are cross-sectional views showing the semiconductormemory device according to the first embodiment;

FIG. 4 is a partially-enlarged cross-sectional view showing memory cellsof the semiconductor memory device according to the first embodiment;

FIGS. 5A and 5B are cross-section& views showing a method formanufacturing the semiconductor memory device according to the firstembodiment;

FIGS. 6A and 6B are cross-sectional views showing the method formanufacturing the semiconductor memory device according to the firstembodiment;

FIGS. 7A and 7B are cross-sectional views showing the method formanufacturing the semiconductor memory device according to the firstembodiment;

FIGS. 8A and 8B are cross-sectional views showing the method formanufacturing the semiconductor memory device according to the firstembodiment;

FIGS. 9A and 9B are cross-sectional views showing the method formanufacturing the semiconductor memory device according to the firstembodiment;

FIGS. 10A and 10B are cross-section& views showing the method formanufacturing the semiconductor memory device according to the firstembodiment;

FIG. 11 is a cross-sectional view showing a semiconductor memory deviceaccording to a comparative example; and

FIG. 12 is a plan view showing a semiconductor memory device accordingto a second embodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, a semiconductor memory deviceincludes a substrate, a first interconnect provided on one side of thesubstrate in a first direction, a second interconnect provided on theone side of the first interconnect, a plurality of third interconnectsextending in a second direction, being arranged to be separated fromeach other along the first direction, and being provided on the one sideof the second interconnect, the second direction crossing the firstdirection, a fourth interconnect provided on the one side of the thirdinterconnects; a semiconductor member extending in the first directionand piercing the plurality of third interconnects, one end portion ofthe semiconductor member being connected to the second interconnect, acharge storage member provided between the semiconductor member and oneof the plurality of third interconnects, and a conductive memberconnected between the first interconnect and the fourth interconnect andinsulated from the second interconnect and the plurality of thirdinterconnects. One of the plurality of third interconnects is disposedon two second-direction sides of the conductive member. Portions of theone of the plurality of third interconnects disposed on the twosecond-direction sides of the conductive member are formed as one body.

First Embodiment

Embodiments of the invention will now be described with reference to thedrawings.

First, a first embodiment will be described.

FIG. 1 is a plan view showing a semiconductor memory device according tothe embodiment.

FIG. 2 is a cross-sectional view showing the semiconductor memory deviceaccording to the embodiment.

FIGS. 3A and 3B are cross-sectional views showing the semiconductormemory device according to the embodiment.

FIG. 4 is a partially-enlarged cross-sectional view showing memory cellsof the semiconductor memory device according to the embodiment.

FIG. 2 shows a YZ cross section parallel to word lines WL describedbelow; and FIGS. 3A and 3B show an XZ cross section parallel to bitlines 52 described below. FIG. 3A shows a 5memory cell region RMC; andFIG. 3B shows a through-via region RV. The drawings are schematic; and,for example, the numbers and dimensional ratios of the components do notalways match between the drawings.

As shown in FIG. 1, FIG. 2, and FIGS. 3A and 3B, a semiconductorsubstrate 10 made of, for example, silicon is provided in thesemiconductor memory device 1 according to the embodiment.

In the specification hereinbelow, an XYZ orthogonal coordinate system isemployed for convenience of description. Two mutually-orthogonaldirections parallel to an upper surface 10 a of the semiconductorsubstrate 10 are taken as an “X-direction” and a “Y-direction;” and adirection perpendicular to the upper surface 10 a, i.e., the verticaldirection, is taken as a “Z-direction.” In the specification, althoughthe direction in the Z-direction in which the upper surface 10 a facesalso is called “up” and the reverse direction also is called “down,”this differentiation is for convenience and is independent of thedirection of gravity.

In the upper surface 10 a of the semiconductor substrate 10, a memoryarray region RA is set; and a peripheral circuit region RC is set aroundthe memory array region RA. A row decoder RD is formed in a region ofthe peripheral circuit region RC positioned on one Y-direction side ofthe memory array region RA. The row decoder RD is a portion of a controlcircuit controlling the memory cells described below.

In the memory array region RA, a STI (Shallow Trench Isolation(element-separating insulating film)) 12 is selectively provided in theupper layer portion of the semiconductor substrate 10. The upper layerportion of the semiconductor substrate 10 is partitioned into multiplesemiconductor regions 13 by the STI 12. A source layer 14 and a drainlayer 15 are formed inside at least a portion of the semiconductorregions 13. A gate insulating film 16 and a gate electrode 17 areprovided on the semiconductor substrate 10 in a region directly above aregion between the source layer 14 and the drain layer 15. Thereby,multiple field effect transistors 18 are formed in the upper surface 10a of the semiconductor substrate 10.

An inter-layer insulating film 60 that is made of, for example, siliconoxide (SiO) is provided on the semiconductor substrate 10. For example,multiple layers, e.g., three layers, of interconnects 22 are providedinside the inter-layer insulating film 60. A contact 23 is connectedbetween the semiconductor substrate 10 and the interconnect 22 of thelowermost layer. A via 24 is connected between the interconnects 22separated in the Z-direction. An integrated circuit 20 is formed of thetransistors 18, the interconnects 22, the contacts 23, and the vias 24.The integrated circuit 20 is another portion of the control circuitdescribed above and is, for example, a sense amplifier. Thearrangements, sizes, and connectional relationships of the transistors18, the interconnects 22, the contacts 23, and the vias 24 shown in FIG.2 and FIGS. 3A and 3B are schematic.

A buried source line 31 is provided on the interconnect 22 of theuppermost layer. The buried source line 31 is, for example, a two-layerfilm including a lower layer portion made of tungsten (W) and an upperlayer portion made of silicon (Si). The buried source line 31 is dividedinto multiple portions in the Y-direction, is disposed in the memorycell region RMC, and is not disposed in the through-via region RV. Apotential is supplied to each portion of the buried source line 31 fromthe integrated circuit 20. If the buried source line 31 has a holethrough which a through-via 44 described below can pass, the buriedsource line 31 may not be divided into the multiple portions in theY-direction.

A stacked body 32 is provided on the buried source line 31. For example,an insulating film 33 that is made of silicon oxide and an electrodefilm 34 that is made of a conductive material are stacked alternatelyalong the Z-direction in the stacked body 32.

Multiple insulating plates 36 are provided inside the stacked body 32.For example, the insulating plates 36 are made from silicon oxide; andthe lower ends of the insulating plates 36 contact the buried sourceline 31. The configurations of the insulating plates 36 are plateconfigurations spreading along the YZ plane. The stacked body 32 isdivided into multiple portions in the X-direction by the insulatingplates 36; and the configuration of each of the electrode films 34 is aninterconnect configuration extending in the Y-direction.

An insulating member 37 that extends in the Y-direction is providedbetween the insulating plates 36 adjacent to each other in theX-direction. For example, the insulating member 37 is positioned at thecenter between the insulating plates 36 adjacent to each other in theX-direction. The insulating member 37 is disposed inside the upperportion of the stacked body 32 and divides, into two along theX-direction, the electrode films 34 of one or more layers from the top.The divided electrode films 34 function as upper selection gate linesSGD. FIG. 1 shows an example in which the insulating members 37 dividethe electrode films 34 of three layers from the top. FIGS. 3A and 3Bshow an example in which the insulating members 37 divide the electrodefilm 34 of one layer from the top.

A real staircase region RSR, a pillar placement region RP, and a dummystaircase region RSD are provided in the memory array region RA and arearranged in this order along the Y-direction. In other words, the realstaircase region RSR and the dummy staircase region RSD are disposed onthe two Y-direction sides of the pillar placement region RP. Asdescribed below, the stacked body 32 is patterned into a staircaseconfiguration in the real staircase region RSR and in the dummystaircase region RSD.

In the pillar placement region RP, silicon pillars 41 that extend in theZ-direction are provided inside the stacked body 32. The silicon pillar41 is made of polysilicon; and the configuration of the silicon pillar41 is a circular tube having a plugged lower end portion. The lower endof the silicon pillar 41 is connected to the buried source line 31; andthe upper end of the silicon pillar 41 reaches the upper surface of thestacked body 32. A memory film 42 is provided on the side surface of thesilicon pillar 41. The memory cell region RMC, the through-via regionRV, and the memory cell region RMC are provided in the pillar placementregion RP and are arranged in this order along the Y-direction. In otherwords, the through-via region RV is disposed between the memory cellregions RMC of two locations separated in the Y-direction.

In the memory cell region RMC, when viewed from the Z-direction, thesilicon pillars 41 are arranged periodically along multiple columns,e.g., four columns, between the insulating plate 36 and the insulatingmember 37. Each column extends in the Y-direction; and the positions ofthe silicon pillars 41 are shifted one-half period in the Y-directionbetween the mutually-adjacent columns. On each of the silicon pillars41, a plug 51 is provided; and the bit line 52 that extends in theX-direction is provided on the plug 51. Thereby, the silicon pillar 41is connected to the bit line 52 via the plug 51. In FIG. 1, thecomponents that are disposed higher than the stacked body 32 are notillustrated.

In the through-via region RV, the through-via 44 that extends in theZ-direction and pierces the stacked body 32 is provided. In thethrough-via 44, for example, a barrier metal layer that is made oftitanium nitride is formed on the side surface and lower surface of amain portion made of tungsten. The upper end of the through-via 44reaches the upper surface of the stacked body 32; and the lower end ofthe through-via 44 is connected to the interconnect 22 of the uppermostlayer of the integrated circuit 20. For example, the through-via 44 isdisposed at the Y-direction central portion of the pillar placementregion RP.

For example, an insulating film 45 that is made of silicon oxide isprovided on the side surface of the through-via 44. The through-via 44is insulated from the electrode films 34 by the insulating film 45. Thethickness of the insulating film 45 is set to a thickness such that thenecessary breakdown voltage between the electrode film 34 and thethrough-via 44 can be realized. The through-via 44 passes between theportions of the buried source line 31, and is separated and insulatedfrom the buried source line 31.

The through-via 44 is disposed to divide the insulating member 37. Inother words, the insulating members 37 are provided respectively on thetwo Y-direction sides of the through-via 44; and the through-via 44 isdisposed between these insulating members 37. More specifically, each ofthe insulating members 37 is divided by the through-via 44 and theinsulating film 45 into a portion 37 a on the real staircase region RSRside and a portion 37 b on the dummy staircase region RSD side; and thethrough-via 44 is disposed between the portion 37 a and the portion 37b. Accordingly, the through-via 44 is disposed between the two electrodefilms 34 of the uppermost level divided in the X-direction by theinsulating members 37. For example, a central axis 44 c of thethrough-via 44 extending in the Z-direction passes through the regionbetween the insulating members 37; and a central axis 37 c of theinsulating members 37 extending in the Y-direction passes through thethrough-via 44. When viewed from the Z-direction, the through-via 44pierces the electrode film 34 but does not divide the electrode film 34.Therefore, all of the electrode films 34 are disposed on the twoY-direction sides of the through-via 44. Also, the portions of each ofthe electrode films 34 disposed on the two Y-direction sides of thethrough-via 44 are formed integrally as one electrode film.

An intermediate interconnect 54, a plug 55, an intermediate interconnect56, and a plug 57 are provided above the through-via 44. The position ofthe intermediate interconnect 56 in the Z-direction is the same as theposition of the bit lines 52. An upper layer interconnect 61 is providedon the plug 57 over the entire region of the semiconductor memory device1. The through-via 44 is connected to one upper layer interconnect 61via the intermediate interconnect 54, the plug 55, the intermediateinterconnect 56, and the plug 57. Accordingly, one upper layerinterconnect 61 is connected to the interconnect 22 of the integratedcircuit 20 via the through-via 44. The interconnect 22 is connected tothe source layer 14, the drain layer 15, or the gate electrode 17 of thetransistor 18. Thus, a power supply potential or a signal potential isapplied to the integrated circuit 20 via the upper layer interconnect 61and the through-via 44.

Although the silicon pillars 41 may be provided in the through-viaregion RV as well, the silicon pillars 41 are not provided in the regionwhere the through-via 44 and the insulating film 45 are provided or inthe periphery of the region where the through-via 44 and the insulatingfilm 45 are provided. Therefore, the number of columns of the siliconpillars 41 in the through-via region RV is less than the number ofcolumns of the silicon pillars 41 in the memory cell region RMC. Also,the plugs 51 and the bit lines 52 are not provided above the siliconpillars 41 provided in the through-via region RV.

In the dummy staircase region RSD and the real staircase region RSR ofthe memory array region RA, the configuration of the stacked body 32 isa staircase configuration in which a step 39 is formed every electrodefilm 34. The numerals of each step 39 in FIG. 1 show the order countedfrom the top of the electrode film 34 forming the step 39. In the realstaircase region RSR, a contact 59 is provided in the region directlyabove each step 39 and is connected to the electrode film 34 formingeach step 39. The electrode films 34 are connected to the row decoder RDvia the contacts 59 provided in the real staircase region RSR. On theother hand, in the dummy staircase region RSD, contacts that areconnected to each of the electrode films 34 are not provided.

The buried source line 31, the stacked body 32, the plugs 51, the bitlines 52, the intermediate interconnect 54, the plug 55, theintermediate interconnect 56, the plug 57, the contacts 59, and theupper layer interconnect 61 are buried inside the inter-layer insulatingfilm 60.

As shown in FIG. 4, for example, a core member 71 that is made ofsilicon oxide is provided inside the circular tubular silicon pillar 41.The silicon pillar 41 may be a circular column;

and the core member 71 may not be provided. A tunneling insulating film72 is provided on the side surface of the silicon pillar 41. Theconfiguration of the tunneling insulating film 72 is a circular tube.Although the tunneling insulating film 72 normally is insulative, thetunneling insulating film 72 is a film in which a tunneling current iscaused to flow when a prescribed voltage within the range of the drivevoltage of the semiconductor memory device 1 is applied; and thetunneling insulating film 72 is formed of, for example, silicon oxide.

A charge storage film 73 is provided on the side surface of thetunneling insulating film 72. The configuration of the charge storagefilm 73 is a circular tube. The charge storage film 73 is a film thatcan store a charge and is formed of, for example, silicon nitride. Thecharge storage film 73 may be formed of a conductive material such aspolysilicon, etc. In such a case, the charge storage film 73 is dividedevery electrode film 34 in the Z-direction. A low dielectric constantlayer 74 is provided on the side surface of the charge storage film 73.The low dielectric constant layer 74 is formed of, for example, siliconoxide.

On the other hand, a high dielectric constant layer 75 is provided onthe upper surface of the electrode film 34, on the lower surface of theelectrode film 34, and on the side surface of the electrode film 34facing the silicon pillar 41. The high dielectric constant layer 75 isformed of a material having a relative dielectric constant that ishigher than the relative dielectric constant of silicon oxide and isformed of, for example, aluminum oxide (AlO). A blocking insulating film76 is formed of the low dielectric constant layer 74 and the highdielectric constant layer 75. The blocking insulating film 76 is a filmin which a current substantially does not flow even when a voltagewithin the range of the drive voltage of the semiconductor memory device1 is applied. The memory film 42 is formed of the tunneling insulatingfilm 72, the charge storage film 73, and the blocking insulating film76.

A main portion 34 a that is made of, for example, tungsten and a barriermetal layer 34 b that is made of, for example, titanium nitride (TiN)are provided in the electrode film 34. The barrier metal layer 34 b isprovided on the upper surface of the main portion 34 a, on the lowersurface of the main portion 34 a, and on the side surface of the mainportion 34 a facing the silicon pillar 41.

In the memory cell region RMC, the silicon pillars 41 are connectedbetween the buried source line 31 and the bit lines 52. The electrodefilm 34 of one or multiple levels from the top of the stacked body 32,i.e., the electrode film 34 that is divided into a line-and-spaceconfiguration by the insulating plates 36 and the insulating members 37,functions as the upper selection gate line SGD; and an upper selectiongate transistor STD is configured at each crossing portion between theupper selection gate line SGD and the silicon pillars 41.

For the electrode films 34 that are divided by the insulating plates 36but not divided by the insulating members 37, the electrode film 34 ofone or multiple levels from the bottom functions as a lower selectiongate line SGS; and a lower selection gate transistor STS is configuredat each crossing portion between the lower selection gate line SGS andthe silicon pillars 41. The electrode films 34 other than the lowerselection gate line SGS and the upper selection gate line SGD functionas the word lines WL; and a memory cell MC is configured at eachcrossing portion between the word lines WL and the silicon pillars 41.

Thereby, a NAND string is formed by the multiple memory cells MC beingconnected in series along each of the silicon pillars 41 and by thelower selection gate transistor STS and the upper selection gatetransistor STD being connected to the two ends the silicon pillar 41. Onthe other hand, NAND strings are not formed for the silicon pillars 41provided in the through-via region RV because the silicon pillars 41 arenot connected to the bit lines 52.

A method for manufacturing the semiconductor memory device according tothe embodiment will now be described.

FIGS. 5A and 5B to FIGS. 10A and 10B are cross-sectional views showingthe method for manufacturing the semiconductor memory device accordingto the embodiment.

First, by normal methods as shown in FIGS. 5A and 5B, the transistors 18are formed in the surface of the semiconductor substrate 10; and thecontacts 23, the interconnects 22, the vias 24, etc., are formed on thesemiconductor substrate 10 and buried in an inter-layer insulating film80. Thereby, the integrated circuit 20 is formed. Then, for example, theburied source line 31 is formed on the inter-layer insulating film 80 bystacking a lower layer portion made of tungsten and an upper layerportion made of amorphous silicon.

Continuing, the stacked body 32 is formed by alternately stacking theinsulating film 33 made of, for example, silicon oxide (SiO) and asacrificial film 81 made of, for example, silicon nitride (SiN). Then,the step 39 is formed every sacrificial film 81 by patterning the twoY-direction end portions of the stacked body 32 into staircaseconfigurations. Then, an inter-layer insulating film 82 is formed tobury the stacked body 32; and the upper surface is planarized.

Then, as shown in FIGS. 6A and 6B, a trench 83 that extends in theY-direction is formed by selectively removing the inter-layer insulatingfilm 82, the sacrificial film 81 of one or multiple layers from the top,and the insulating film 33 of one or multiple layers from the top. Then,the insulating member 37 is formed by filling, for example, siliconoxide into the trench 83. The insulating member 37 divides thesacrificial film 81 of one or multiple layers from the top. An examplein which the sacrificial film 81 of the uppermost layer is divided isshown in FIG. 6B,

Continuing as shown in FIGS. 7A and 7B, a via hole 85 is formed topierce the inter-layer insulating film 82 and the stacked body 32, passbetween the portions of the buried source line 31, reach theinterconnect 22 of the uppermost layer of the integrated circuit 20, anddivide the insulating member 37 (referring to FIG. 6B) in theY-direction. Then, the insulating film 45 is formed by depositingsilicon oxide on the entire surface. The insulating film 45 is formedalso on the inner surface of the via hole 85.

Then, as shown in FIGS. 8A and 8B, the portion of the insulating film 45formed on the bottom surface of the via hole 85 is removed by etchingsuch as RIE (Reactive Ion Etching), etc. Thereby, the interconnect 22 isexposed at the bottom surface of the via hole 85.

Continuing as shown in FIGS. 9A and 9B, a barrier metal layer (notillustrated) is formed on the inner surface of the via hole 85 bydepositing, for example, titanium nitride; and a main portion (notillustrated) is filled into the via hole 85 by depositing, for example,tungsten. Then, the tungsten and the titanium nitride that are formed onthe inter-layer insulating film 82 are removed by performingplanarization such as CMP (Chemical Mechanical Polishing), etc. Thereby,the through-via 44 is formed inside the via hole 85.

Then, as shown in FIGS. 10A and 10B, an inter-layer insulating film 86for adjusting the height of the memory holes MH (referring to FIG. 4) isformed on the inter-layer insulating film 82.

Continuing as shown in FIG. 4, the memory hole MH that extends in theZ-direction is formed to pierce the inter-layer insulating films 86, 82,and 80 and the stacked body 32 (referring to FIGS. 10A and 10B). Then,the low dielectric constant layer 74 that is made of silicon oxide isformed by oxidizing the inner surface of the memory hole MH. Then, thecharge storage film 73, the tunneling insulating film 72, the siliconpillar 41, and the core member 71 are formed in this order on thesurface of the low dielectric constant layer 74 inside the memory holeMH.

Then, as shown in FIG. 1, FIG. 2, FIGS. 3A and 3B, and FIG. 4, slits STthat extend in the Y-direction are formed in the inter-layer insulatingfilms 86, 82, and 80 (referring to FIGS. 10A and 10B) and the stackedbody 32. Then, the sacrificial films 81 are removed by performing wetetching via the slits ST. Thereby, a space 87 is formed between theinsulating films 33.

Continuing, the high dielectric constant layer 75 is formed on the innersurface of the space 87 by depositing aluminum oxide via the slits ST.The blocking insulating film 76 is formed of the low dielectric constantlayer 74 and the high dielectric constant layer 75. Then, the barriermetal layer 34 b is formed on the surface of the high dielectricconstant layer 75 by depositing titanium nitride via the slits ST. Then,the main portion 34 a is formed inside the space 87 by filling tungstenvia the slits ST. The electrode film 34 is formed of the barrier metallayer 34 b and the main portion 34 a. Then, the insulating plate 36 isformed by filling silicon oxide into the slits ST.

Then, contacts (not illustrated) that pierce the inter-layer insulatingfilms 86, 82, and 80 and reach the integrated circuit 20 are formedaround the stacked body 32. The contacts may be formed simultaneouslywith the through-via 44. Then, the contacts 59 that reach the steps 39of the stacked body 32 are formed in the real staircase region RSR.Then, an inter-layer insulating film is further formed on theinter-layer insulating film 86; and the plugs 51, the bit lines 52, theintermediate interconnect 54, the plug 55, the intermediate interconnect56, the plug 57, etc., are formed. Then, the upper layer interconnect 61is formed and connected to the through-via 44 via the plug 57, theintermediate interconnect 56, the plug 55, and the intermediateinterconnect 54. The inter-layer insulating films 80, 82, and 86 areused to form a portion of the inter-layer insulating film 60. Thus, thesemiconductor memory device 1 according to the embodiment ismanufactured.

Effects of the embodiment will now be described.

In the semiconductor memory device 1 according to the embodiment,because the integrated circuit 20 is provided between the semiconductorsubstrate 10 and the stacked body 32, the surface area of the peripheralcircuit region RC can be reduced; and the chip surface area of thesemiconductor memory device 1 can be reduced. As a result, theintegration of the memory cells improves. Also, because the through-via44 that pierces the stacked body 32 is provided, the power supplypotential or the signal potential can be supplied from above the stackedbody 32 to the integrated circuit 20 provided directly under the stackedbody 32. In such a case, by using the through-via 44 in combination withthe contacts provided around the stacked body 32 described above, it iseasy to supply the power supply potential or the signal potential to anyposition of the integrated circuit 20; and the degrees of freedom of thelayout of the integrated circuit 20 increase. The through-via 44 may beformed also in the dummy staircase region RSD in addition to the pillarplacement region RP. Thereby, the degrees of freedom of the layout ofthe integrated circuit 20 increase even further.

In the case where the integrated circuit 20 is provided below thestacked body 32, although it is favorable to use a material having highheat resistance such as tungsten, etc., as the interconnect material,materials that have high heat resistance generally have high electricalresistivities. Therefore, if it is attempted to provide the contactsonly around the stacked body 32 and to supply the power supplypotential, etc., from the upper layer interconnect, the distance fromthe contacts to the central portion of the integrated circuit 20lengthens; and the operations of the integrated circuit 20 areundesirably slow. In the embodiment, because the through-via 44 isprovided to pierce the stacked body 32, the prescribed potential can bedirectly supplied to the central portion of the integrated circuit 20via the through-via 44; and the operation speed of the integratedcircuit 20 can be increased.

In the embodiment, the through-via 44 is formed not to divide theelectrode films 34. Thereby, a configuration for connecting the dividedelectrode films 34 to each other is unnecessary; and the integration ofthe memory cells improves. This effect also is described in acomparative example described below.

In the embodiment, the through-via 44 is disposed at a position dividingthe insulating member 37. The insulating members 37 are for dividing theupper selection gate line SGD;

and the regions directly under the insulating members 37 originally weredead space where the memory cells are not formed. Therefore, by formingthe through-via 44 to be interposed between the insulating members 37,the dead space can be utilized effectively; and the decrease of theintegration of the memory cells due to the through-via 44 being providedcan be suppressed.

In the embodiment, the insulating film 45 is provided on the sidesurface of the through-via 44. Thereby, the through-via 44 can beinsulated reliably from the electrode films 34 using a small surfacearea. Thereby, the integration of the memory cells can be increased.

In the embodiment, in the processes shown in FIGS. 7A and 7B, the viahole 85 is formed by etching the insulating films 33 made of siliconoxide and the sacrificial films 81 made of silicon nitride. Then,subsequently, the sacrificial films 81 are replaced with the electrodefilms 34. Therefore, the etching is easy compared to the case where thevia hole 85 is formed after the electrode films 34 made of a metalmaterial such as tungsten or the like are formed.

In the embodiment, the through-via 44 does not divide the sacrificialfilms 81 and is formed not to be interposed in the formation regions ofthe slits ST as well. Therefore, the through-via 44 does not obstructthe removal of the sacrificial films 81 via the slits ST and does notobstruct the filling of the electrode films 34 after the sacrificialfilms 81 are removed.

In the embodiment, the memory holes MH and the silicon pillars 41 areformed in the through-via region RV as welt. Thereby, when thesacrificial films 81 are removed via the slits ST, similarly to thememory cell region RMC, the silicon pillars 41 are used as posts even inthe through-via region RV; and sagging of the insulating film 33 can besuppressed.

Although an example is shown in the embodiment in which the through-via44 is formed to divide the insulating member 37, this is not limitedthereto; and if the through-via 44 is formed not to divide the electrodefilms 34, the through-via 44 may be disposed at a position separatedfrom the insulating member 37. Although an example is shown in theembodiment in which the row decoder RD is provided on one Y-directionside of the memory array region RA, the row decoder RD may be providedon the two Y-direction sides. In such a case, contacts may be providedin the dummy staircase region RSD as well; and each of the electrodefilms 34 may be connected to either one of the row decoders RD providedon the two Y-direction sides.

A comparative example will now be described.

FIG. 11 is a cross-sectional view showing a semiconductor memory deviceaccording to the comparative example.

In the semiconductor memory device 101 according to the comparativeexample as shown in FIG. 11, a stacked body in which the insulating film33 and the electrode film 34 are stacked alternately is formed; andsubsequently, a conductive member 144 for connecting the upper layerinterconnect 61 to the interconnect 22 of the integrated circuit 20 isformed. In such a case, because it is difficult to simultaneously etchthe insulating films 33 made of silicon oxide and the electrode films 34made of a metal material, the conductive member 144 is formed afterdividing the electrode films 34 and burying the electrode films 34 withsilicon oxide. Accordingly, the electrode films 34 are undesirablydivided in the Y-direction.

However, because the row decoder RD is provided on only one Y-directionside of the stacked body 32, it is necessary to connect the dividedportions of the electrode film 34 to each other via upper interconnectsto connect the entire electrode film 34 to the row decoder RD. To drawout the multiple electrode films 34 stacked in the Z-direction to theupper interconnects, it is necessary to pattern the stacked body 32 intoa staircase configuration; and the surface area for the staircaseconfiguration becomes necessary. As a result, in the semiconductormemory device 101, there are more regions where the memory cells are notformed; and the integration is low.

Conversely, in the embodiment, because the electrode films 34 are notdivided by the through-via 44, the upper interconnects that connect thedivided portions of the electrode films 34 to each other areunnecessary; and it is unnecessary to pattern the stacked body 32 into astaircase configuration to draw out the electrode films 34 to the upperinterconnects. Therefore, the chip surface area is small; and theintegration is high.

Second Embodiment

A second embodiment will now be described.

FIG. 12 is a plan view showing a semiconductor memory device accordingto the embodiment.

In the semiconductor memory device 2 according to the embodiment asshown in FIG. 12, the multiple through-vias 44 are provided along eachof the insulating members 37. For each of the insulating members 37, forexample, the multiple through-vias 44 are arranged periodically. Whenviewed from the Z-direction as shown in FIG. 12, for example, thethrough-vias 44 may be arranged in a staggered configuration. Theinsulating film 45 is provided around each of the through-vias 44. Thethrough-vias 44 may be disposed at the vicinity of a shunt interconnect(not illustrated), and may be disposed in regions between the pillarplacement region RP and the real staircase region RSR or between thepillar placement region RP and the dummy staircase region RSD. Althoughthe arrangement of the through-vias 44 is not limited to the exampledescribed above, it is favorable for the arrangement to be optimizedinside the pillar placement region RP. Otherwise, the configuration, themanufacturing method, and the effects of the embodiment are similar tothose of the first embodiment described above.

According to the embodiments described above, a semiconductor memorydevice having high integration can be realized.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. A semiconductor memory device, comprising: asubstrate; a first interconnect provided on one side of the substrate ina first direction; a second interconnect provided on the one side of thefirst interconnect; a plurality of third interconnects extending in asecond direction, being arranged to be separated from each other alongthe first direction, and being provided on the one side of the secondinterconnect, the second direction crossing the first direction; afourth interconnect provided on the one side of the third interconnects;a semiconductor member extending in the first direction and piercing theplurality of third interconnects, one end portion of the semiconductormember being connected to the second interconnect; a charge storagemember provided between the semiconductor member and one of theplurality of third interconnects; and a conductive member connectedbetween the first interconnect and the fourth interconnect and insulatedfrom the second interconnect and the plurality of third interconnects,one of the plurality of third interconnects being disposed on twosecond-direction sides of the conductive member, and portions of the oneof the plurality of third interconnects disposed on the twosecond-direction sides of the conductive member being formed as onebody.